Isomerization of ricinoleic compounds



Patented Feb. 1, 1944 UNITED STATES PATENT 2,340,745 FFiCE ISOMERIZA'I'ION 0F RIGINOLEIO COMPOUNDS William E. llanford, Richard S. Schreiber, and- Hugh W. Gray, Wilmington, Delaauignora to E. I. (in Pont de Nemoura- A: Company, Wilmington, Del., a corporation of Delaware No Drawing. Application November 14,

Serial No. 419.0

1941p I 80 I.

Claims. (c1. zoo-405.6)

This invention relates to the preparation of 12- ketostearic acid derivatives by caialytically isomerizing ricinoleic compounds.

Various methods have been utilized heretofore for preparing l2-ketostearic acid derivatives from castor oil. These include a two-step processwhich has found limited commercial use, namely, the catalytic hydrogenaflon of castor oil to 12- hydroxystearin, followed by catalytic dehydrogenation to 12-ketostearin. Alternatively, the l2-hydroxystearin can be oxidized by chemical means to l2-ketostearin using such reagents as chromic acid. Obviously such two-step procedures are deficient in numerous respects and would necessarily defer to a satisfactory one-step isomerization procedure, e. g., the direct rearrangement of castor oil to l2-ketostearin. At-

tempts at realizing this isomerization have not been particularly successful in a practical sense.

Althou h l2-ketostearic acid derivatives have been identified in the pyrolysis products of the barium salts of castor oil acids, the yields are quite low and the presence of accompanying degradation products complicates the isolation procedures. Attempts at effecting isomerizationby heating castor oil with hydrogenationcatalysts have given inexplicable results. Thus, Belopolsky and Maksimov, Chem. Abs. 31, 7397 (1937), heated castor oil at 200 to 300 C. with a nickel catalyst prepared from nickel formate and obtained only traces of l2-ketostearic acid, the predominating reaction products being those resulting from dehydrogenation and pyrolysis.

This invention has as an object to provide a new and improved process for the production of izeketostearic' acidderivatives from rlcinoleic acid compounds. Another object is to prepare illustrate the preferred embodiments of thisinl2-ketostearic acid derivatives from castor oil by descriptionoftheinvention.

The above and other objects appearing hereinafter are by. the following inventlcn which comprises heating the ricincleic compoimd either within, nickel or cobalt catalyst prepared either by reducing a nickel or, cobalt salt with sodium-naphthalene or by extracting with alkali the alkali soluble component of an all y of nickel or cobalt with an alkali soluble met and. if the ricinoleic compound treated is not an ester of a lower mcnohydrlc'alcchoi. convertin product to such an ester by disaolvingitinalowermonohydrlc alcohohnltering oifth nickel or cobcltcatalyit. adding anester nterchange catalyst to the solution. heating it l2-kctcctearicacldiatheprcductdeaireditmay beoszeinea-mmmemueem an efllcient and commercially useful method.

Other objects will be apparent from the following l2-ketostearaie by methods wellv known to the art.

In general, in practicing this'invention with castor oil to triglyceride of ricinoleic acid), the castor oil is heated to between 225 C. and 300 C. for from 2 to 5 hours either with an elementary nickel or cobalt catalyst, prepared as hereinbefore described. The isomerized product is dissolved in an amount of a lower monohydric alcohol which is at least stoichiometrically equivalent to its l2-ketostearic acid content, the solution filtered to remove the nickel or cobalt catalyst, an ester interchange catalyst, e. g., concentrated suiiuricacid, is added, the solution refluxed until alcohol interchange is substantially complete, the glycerin removed by Washing with water, an organic solvent, e. g., benzene, is added,

the extract is dried and distilled under reduced pressure. Pure methyl l2-ketostearate boils at about 200 to 210 C. at 2 to 3 mm. pressure and melts at 42 to 44 C. p

The reaction can be carried out at superatmospheric or at substantially atmospheric pressures,

, satisfactory yields being obtained when the revention and are not to be considered as limitations thereof. Parts are by weight. unless otherwisestated.

Example I A mixture of parts of castor oil and 10 parts of a sodium-naphthalene-reduced nickel catalyst prepared according to U. S. 2,177,412, is placed in a 8138s reaction vessel fitted with a stirrer, air condenser and gas-collecting bottle. The reaction mixture is heated for 6 hours at 230 to 250 C. with stirring, the viscous liquid is cooled to room temperature, and the catalyst removed by filtration. From th reaction mixture there is separated a white crystalline product melting at 70' to iii. C. and identified asl2-keto'stearin.

sam le n a mixture of to parts of methyl ricinoleate and 5 parts of, the sodium-naphthalene-reduced nickel catalyst ofltxamplelisheatedinacloaed metaIreaetionveaelatM CJorIhoui-with- .oviccrouccsltction. 'lhervwtimmixtureicdb.

2 solved in methanol, the catalyst removed by filtration and the methanol solvent evaporated. The resulting semi-crystalline solid is washed naphthalene reduced nickel catalyst of Example I is-heated in a closed metal reaction vessel at 275 C. for 3 hours. The crude product is conwith low-boiling petroleum ther. The material melts at 43 to 46 C. and does not depress the melting point of authentic methyl l2-ketostearate. The ketone number is 160.9, thetheoretical value formethyl lz-ketostearate being 180.

Example 111 A mixture 100 parts oi castor oil and 10 parts of the sodium-naphthalene reduced nickel catalyst of Example I is heated in a closed metal reaction vessel at 250 C. ford hour. The reaction mixture is allowed to cool to room temperature, dissolved in 160 parts of methanol, and filtered to remove the catalyst. After addition of 9 parts of concentrated sulfuric acid the solution is refluxed for hours. The mixture is washed with water, dissolved in benzene, dried over sodium sulfate, and distilled under reduced pressure. There is obtained 43 parts of methyl l2- ketostearate boiling at 183 to 199 C, (2.8 to 4.0

mm., M P. 42' to 465 C.)

Example IV A mixture of 100 parts or castor oil and parts of alloy-skeleton nickel catalyst is heated in .a closed metal reaction vessel for 3 hours at 275 C. The reaction mixture is dissolved in 160 parts of methanol, filtered free of catalyst. and refluxed for 5 hours with 18 parts of concentrated sulfuric acid. The material is washed with water, dried, and distilled. There is obtained 54 parts of methyl lz-ketostearateboiling at 1810 to 202 C. (2.7 to 4.0 mm., M. P. 41' to'44 C.).

The alloy skeleton nickel catalyst of the above example is prepared as follows:

Four hundred fifty four parts of a 50/50 nickelaluminum alloy powder is added insmall ortions to 2454 parts of an approximately 18% aqueous sodium hydroxide solution and the suspension heated ior 4 hours. t The suspended material is allowed to settle and the supernatant caustic containing liquid removed by decantation. The finely divided metallic nickel is washed with water until the washings are neutral to litmus. the finely divided nickel powder is washed. with alcohol until free of water, and stored in alcohol.

Example V A mixture of 100 parts of castor oil and 10 parts or the sodlum-naphthalene-reduced nickel catalyst of Example I is placed in a glass reaction vessel fitted with a sea exit tube open to the atmosphere. The reaction mixture. is heated with stirring for 4% hours at 230 to 275 C. The reaction mixture is filtered and after conversion of the glyceride to the methyl ester by refluxing with methanol in the presence of sulfurlc acid there is obtained 62 parts of methyl 12-ketostearate boiling at 182 to 205 C. (5 mm., M. P. 42 to 45C.)

Example VI Example VII Amixture oi l00partsofcastoroil, loo-parts oi cyclohexene and 10 parts 01 verted to the methyl ester and there is obtained 53 partsof methyl lZ-ketostearate boiling at 190 to 204 C. (3.0 to 3.5 mm.)

Ricinoleic compounds are generally suitable for the practice of this invention. In place of commercial castor oil, which contains from 80 to 85% glyceryl triricinoleate, there can be used either castor oil purified by extraction with petroleum naphtha, or such ricinoleic compounds as methyl, ethyl, propyl, octyl, dodecyl, etc., ricinoleates, ricinoleamide, ricinoleic anhydride, and salts of ricinoleic acid, e. g., sodium, potassium and ammonium ricinoleates, etc.

In the practice of this invention there can be used elementary nickel or cobalt catalysts comminuted at temperatures of about 20 to about 110 C. One of the preferred catalysts is alloyskeleton nickel prepared by caustic extraction of nickel-aluminum alloys at temperatures of about 90 to 100 C. Another preferred catalyst is nickel prepared by the sodium-naphthalene reduction of nickel chloride according to U. S. Patent 2,177,412. The catalysts can be used in the finely divided state or in massive form, e. g.,

pellets. The catalyst can be of the pyrophoric type ormay be stabilized by subjection of the pyrophoric metal to an oxygen containing atmosphere at a temperature below C. It has been found that traces of alkah in the catalyst are beneficial since the activity of the catalyst is thereby enhanced. This activating efiect of alkah can be utilized to render operable catalysts which are otherwise relatively inactive in the isomerlzation of ricinoleic compounds to the corresponding ketostearic compounds. By traces of alkali it is meant amounts of alkah insuflicient to bring about any-substantial hydrolysis or dehydration of the ricinoleic acid ester under the conditions of reaction.

If desired, the ricinoleic compound can be isomerized insolution in a suitable organic solvent, e. g., benzene, acetone, cyclohexane, decahydronaphthalene, etc.

The process of this invention can be operated over a considerable range of temperatures. I Reaction occurs at temperatures as low as 200 C.

As the temperature is raised the rate of reaction increases and it is thereiore preferable to operate at temperatures above 200 C. In most cases the compounds are stable at temperatures up to 350 C. and the process can be operated at temperatures in the range of 200 to 350 C. In general the process is carried out in a closed reaction vessel under the autogenous pressure of the reaction mixture. If desired, however, the process can be operated under superatmospheric pressures developed by the introduction-of inert gases such as nitrogen or carbon dioxide. The reaction also proceeds satisfactorily when run'in an open vessel at atmospheric pressure. It is desirable, though not necessary, to blanket the mixture with an inert atmos here. such as nitrogen or carbon dioxide to avoid any deleterious ell'ectsdue to 7 oxygen at the high temperatures employed. The

reaction is also adaptable to continuous operation by passing the ricinoleate over the nickelfor cobalt catalyst maintained at the proper temperature a mentioned-above. the ketostearic acid derivatives obtained-can be isolated by various a l-t-diltlllation or the ester, crystallization of the free acid, ester, salt, anhydrlde or amide, etc.

The process of this invention is useful in the preparation of 12-ketostearic acid and its derivatives which are valuable intermediates in the preparation of surface-active materials, pharmaceuticals and bifunctionalpolymer ingredients, and in the formulation and compounding of waxes and similar materials.

As many apparently widely diiierent embodiments of this invention may be made without departing from the spirit and scope thereof; it is to be understood that this invention is not to be limited to the specific embodiments shown and described. 4

we claim:

1. .A process for catalytically .isomerizing a ricinoleic compound to l2-ketostearic acid de-' rivatives which comprises heating said ricinoleic compound in the presence only of a catalyst selected from the group consisting of elementary cobalt and nickel, said catalyst being prepared by reacting a salt selected from the group of nickel and cobalt salts with a solution of sodium-naphthalene and elementary cobalt and nickel prepared by treating an alloy selected from the group of cobalt-aluminum and nickel-aluminum a1 loys with a solution of caustic alkali.

2. The process in accordance with claim 1 characterized inthat the catalyst is in the pyrophoriccondition. r

3. The process in accordance with claim 1 characterized inthat the catalyst is one prepared by stabilizing the pyrophoric metal by exposure to an x enontaining atmosphere while maintaining the catalyst mass at a temperature below 50 C.

4. A process for cataLvtically isomerizing a ricinoleic compound ,w 12-ketostearin which-- comprises heating castor oil at a temperature between 200 and 350 C. in the presence only of a-catalyst selected from the class consisting or elementary cobalt and nickel, prepared by reacting a salt selected from the group of nickel and cobalt salts with a solution of sodium-naphthalene and elementary cobalt and nickel prepared by treating an alloy selected from the group of cobalt-aluminum and nickel-aluminumalloys with a solution of caustic alkali.

5. The process in accordance with claim 1 characterized in that the catalyst is selected from nickel and cobalt the class of alloy-skeletoncatalysts.

6. The process in accordance with claim 1 characterized in that the catalyst -is one prepared'by reducing a salt of a metal selected from the class of nickel and cobalt with sodium-naphthalene.

9.'A process for catalytically isomerlzing a ricinoleic compound to 12-ketostearic acid de rivatives which comprises heating castor oil in the presence only of a catalyst selected irom the class of elementary nickel and cobalt catalysts prepared by reacting a salt selected from the group of nickel and cobalt salts with a solution of sodium-naphthalene and elementary cobalt and nickel prepared by treating an alloy select ed from the group of cobalt-aluminum and nickel-aluminum alloys with a solution of caustic alkali, heating the resulting 12-ketostearin with a monohydric alcohol in the presence of an alcohol interchange catalyst, and separating the resuiting monohydric alcohol IZ-ketostearate.

10. A process for catalytically' isomerizing' a ricinoleic compound to lz-ketostearlc acid which comprises heating castor oil in the presence only of a catalyst selected from the class of elementary nickel and cobalt catalysts prepared by reacting heating a monohydric alcohol ester of ricinoleic acid in the presence only of a catalyst selected from the class of elementary nickel and cobalt catalysts prepared 'by reacting a salt selected from the group of nickel and cobalt salts with a solution of sodium-naphthalene and elementary cobalt and nickel prepared by treating an alloy selected from the. group of cobalt-aluminum and nickel-aluminum alloys with a solution of caustic alkali, and isolating the resulting monohydric alcohol 12-ketostearate.

12. A process .for catalytic isomerization 12- ketostearic acid which comprises heating a monohydric alcohol ester of ricinoleic acid in the presence only of a catalyst selected from the class of elementary nickel and cobalt catalysts prepared by reacting a salt selected from the group of nickel and cobalt salts with a solution or sodium-naphthalene and elementary cobalt and nickel prepared by treatingan alloy selected from the group of cobalt-aluminum and nickel-aluminumalloys with a solution of caustic alkali,

, removing the catalyst, hydrolyzing the monolay- 'dric alcohol IZ-ketostearate, and recovering the a 12-ketostearlc acid.

'7. A process for catalytically isomerizing aricinoleic compound to ketostearic acid derivatives .which comprises heating said ricinoleic compound in the presence only or an alloy skeleton nickel .catalyst prepared by the caustic extraction of finely divided nickel-aluminum alloy at temperatures of about to C.

. 8. A process for catalytically isomerizing a ricinoleic compound toketostearic acid derivatives which comprises heating said ricinoleic compound in the presence only of a nickel-catalyst prepared by the sodium-naphthalene tion of nickel chloride.

reduc- 1'3. The process with 1 characterized in that the nickel catalyst containstracesofalkali.

14. The process in accordance with claim 'I thattlrecatalystcontainstraces ofalkali. ,"i -15.Theprocesr inaccordancewlthclaim8 characterlzedinthatthecatalystcontainstraces ofalkali. r I WILLIAME. HANFORD.

RICHARD 8.. :lcuneirmenmgnair. 

